Network time slotted protocols are widely used to establish communications between network nodes utilizing a predictable time frame slotting technique for nodes to communicate, where each network node communicates according to predefined time slots. Such protocols generally provide scheduled, contention-free channel access to improve throughput performance compared to carrier sense techniques. These protocols are often employed in the formation of ad hoc wireless communications networks, for example. Ad hoc wireless communications networks are formed dynamically as nodes come within range of existing network resources. These networks may be utilized in many applications to provide communications between lower level devices on the networks such as sensors and upper tier devices communicating with the sensors.
In some applications, routing protocols are created that define relationships in the network and how the network operates as conditions change. For example, each node within the network can have a preferred parent node for communications in an upwards direction and possibly having multiple intermediate nodes and/or child nodes for downward communications.
A multi-hop wireless network consists of a root node, intermediate nodes, and child nodes which are also referred to as leaf nodes. The root node connects the network to an internal or external network. The intermediate node connects the leaf nodes (and other intermediate nodes) to the root node and from there to the internal/external network. The definition of leaf/child nodes is that there are no other nodes connected to these nodes. In beacon channel hopping networks, a coordinator transmits periodic beacons that contain information to facilitate nodes joining and communicating in the network. The information contained in the beacon could be the channels to be used at a specific time, timing information when this beacon is sent, link information, and so forth. To transmit data in these networks, the nodes can then use the link information, which can be a pair of (channel, time) to communicate and send data to their respective neighbors. In order to use the link information, nodes are to be synchronized and receive beacons. Intermediate nodes also transmit beacons and in these beacons, the same information that was sent by the coordinator is repeated. This is to allow other intermediate and leaf/child nodes to connect to the network.